This invention relates to a television system which provides increased vertical resolution and which is compatible with standard color television systems such as NTSC. Standard NTSC television scans 525 lines per frame in the form of two sequential fields of 2621/2 lines. The lines of each field interlace with the lines of the preceding and succeeding fields and the eye integrates these to reduce flicker. However, the line structure is still visible under certain circumstances, and is particularly visible on large-screen television displays viewed from a relatively close distance. The problem is made even more severe by the ultra-large pictures formed by projection-type television displays. The visibility of the line structure is surprising, considering that a composite NTSC signal actually comprises three simultaneous channels of information (one luminance, two chrominance) and therefore represents about 1500 lines per frame. The visibility results from the superposition of the R, G and B signals in triples. It is desirable to increase the effective vertical resolution or definition in a manner compatible with current standard television practice, so that broadcasting of high-resolution signals can begin immediately without seriously degrading the performance of standard television receivers currently in use, and yet be such that when processed by a receiver according to the invention they produce an improved high-resolution picture.